bims-adreca 2024-03-31 papers

bims-adreca

Biomed News

on Adrenal calcium

Issue of 2024–03–31
fiveteen papers selected by
Bakhta Fedlaoui, INSERM

Clinical prediction model for primary aldosteronism subtyping and special focus on adrenal volumetric assessment.
The ex vivo perfused mouse adrenal gland-a new model to study aldosterone secretion.
Conn´s syndrome after kidney transplantation.
Subtype Identification of Surgically Curable Primary Aldosteronism During Treatment With Mineralocorticoid Receptor Blockade.
Accumulating evidence suggests the potential of selective adrenal artery embolization as a standard treatment for primary aldosteronism.
Correction to: Histamine H2‑receptor antagonism improves conduit artery endothelial function and reduces plasma aldosterone level without lowering arterial blood pressure in angiotensin II-hypertensive mice.
Classical and Alternative Pathways of the Renin-Angiotensin-Aldosterone System in Regulating Blood Pressure in Hypertension and Obese Adolescents.
Phosphodiesterases 4B and 4D Differentially Regulate cAMP Signaling in Calcium Handling Microdomains of Mouse Hearts.
TRPM5 activation depends on a synergistic effect of calcium and PKC phosphorylation.
Prediction of endogenous mineralocorticoid receptor activity by depressor effects of mineralocorticoid receptor antagonists in patients with primary aldosteronism.
Effect of adrenocorticotropic hormone stimulation during adrenal vein sampling for the subtyping of primary aldosteronism: a prospective study.
Development of a diagnostic model for pre-washout screening of primary aldosteronism.
TRPV4 Activation during Guinea Pig Airway Smooth Muscle Contraction Promotes Ca2+ and Na+ Influx.
Screening for Primary Aldosteronism by Mass Spectrometry Versus Immunoassay Measurements of Aldosterone: A Prospective Within-Patient Study.
Salt-Sensitive Hypertension and the Kidney.

Hormones (Athens). 2024 Mar 27.

Clinical prediction model for primary aldosteronism subtyping and special focus on adrenal volumetric assessment.

Tugba Barlas, Erhan Turgut Ilgit, Mehmet Koray Akkan, Emetullah Cindil, Isil Imge Gultekin, Hulya Nur Sodan, Mehmet Muhittin Yalcin, Ethem Turgay Cerit, Sinan Sozen, Mujde Akturk, Fusun Toruner, Ayhan Karakoc, Alev Eroglu Altinova.

   PURPOSE: Our aim was to develop a prediction model based on a simple score with clinical, laboratory, and imaging findings for the subtype diagnosis of primary aldosteronism (PA). The contribution of adrenal volumetric assessment to PA subtyping was also investigated.
METHODS: Thirty-five patients with adequate cannulation in adrenal venous sampling (AVS) were included. Laboratory data, the saline infusion test (SIT), and the AVS results of patients with PA were retrospectively evaluated. Volumetric assessment was performed using magnetic resonance imaging (MRI) and the ratio of adrenal volumes was calculated after adjusting for gender- and side-specific mean reference values of both adrenal glands.
RESULTS: The AVS was consistent with unilateral PA in 49% and bilateral in 51% of the patients. Hypertension as a reason for work-up, the highest aldosterone/lowest potassium value higher than 12, the percentage of plasma aldosterone concentration (PAC) reduction after SIT by equal or less than 43.5%, the use of oral potassium replacement, unilateral disease at pre-AVS imaging, and a ratio of adjusted adrenal volumes equal to or below 1.7 were indicative of unilateral disease in univariate logistic regression analysis concerning the distinction of PA subtyping (p < 0.05). Multivariate logistic regression analysis also revealed that adrenal volumetric assessment has an impact on PA subtyping (p < 0.05). In the prediction model, when each of the six parameters that were significant in the univariate logistic regression analysis was assigned one point, < 4 predicted bilateral PA, whereas ≥ 4 predicted unilateral PA (AUC:0.92, p < 0.001).
CONCLUSION: This prediction model before AVS may serve as a convenient and practical approach, while an adjusted adrenal volumetric assessment can make a positive contribution to PA subtyping.

Keywords:  Adrenal venous sampling; Adrenal volume; Aldosterone producing adenoma; Bilateral adrenal hyperplasia; Prediction model; Primary aldosteronism

DOI:  https://doi.org/10.1007/s42000-024-00548-9
Pflugers Arch. 2024 Mar 28.

The ex vivo perfused mouse adrenal gland-a new model to study aldosterone secretion.

Allein Plain, Laura Knödl, Ines Tegtmeier, Sascha Bandulik, Richard Warth.

  Aldosterone is a steroid hormone that is important for maintaining the volume and ionic composition of extracellular fluids and is produced in the zona glomerulosa of the adrenal cortex. The basic mechanisms controlling aldosterone secretion are known. However, more detailed studies on the regulation of aldosterone secretion often fail due to the lack of suitable models: although secretion can be studied in cultured adrenocortical cells under defined conditions, the differentiation status of the cells is difficult to control and the complex anatomy of the adrenal cortex is lost. In living animals, the physiological context is intact, but the influences are manifold and the examination conditions cannot be sufficiently controlled. One method that closes the gap between cell models and studies in living animals is the isolated perfused adrenal gland. In the past, this method has provided important data on the pathophysiology of adrenal glands from larger animals, but the technique was not used in mice. Here, we developed a method for isolation and perfusion of the mouse adrenal gland to study aldosterone secretion. This technique preserves the complex anatomical and functional context of the mouse adrenal cortex, to ensure defined experimental conditions and to minimize extra-adrenal influences. Initial series of experiments with the ex vivo perfused mouse adrenal gland show that this model offers the possibility for unique insights into pathophysiological regulatory principles and is suitable for the use of genetically modified mouse models.

Keywords:  Adrenal cortex; Aldosteronism; Mouse models; Pathophysiology; Secretion

DOI:  https://doi.org/10.1007/s00424-024-02950-z
Bratisl Lek Listy. 2024 ;125(4): 258-263

Conn´s syndrome after kidney transplantation.

Michaela Javorkova, Andrea Bystricanova, Martina Cirbusova, Marcela Cvoligova, Martin Chrastina, Juraj Maris, Janka Otavkova, Zuzana Zilinska.

Conn's syndrome, defined as unilateral aldosterone-producing adenoma, accounts for 35-40% of cases of primary hyperaldosteronism. Primary hyperaldosteronism typically occurs in younger patients with poorly controlled arterial hypertension due to extracellular fluid retention, in whom at least a triple combination of antihypertensives, including a diuretic, is needed to maintain normotension. The clinical picture of arterial hypertension may be complemented by symptoms associated with hypokalaemia, such as weakness, fatigue, palpitations, convulsions, polydipsia, or polyuria. In addition to arterial hypertension and hypokalaemia, the diagnosis of Conn's syndrome relies on examination of serum renin and aldosterone concentrations, plasma renin activity, exercise or furosemide stimulation tests, and imaging studies, preferably computed tomography. The method of treatment of Conn's syndrome is adrenalectomy. In patients with primary hyperaldosteronism with underlying bilateral adrenal cortical hyperplasia or patients contraindicated for surgery, mineralocorticoid receptor antagonists are administered in combination with antihypertensives targeted for optimal blood pressure control.In the group of patients after kidney transplantation, the exact incidence of primary hyperaldosteronism is unknown. Based on a cross-sectional study performed in 2020, it is estimated to be approximately 15% in the group of patients with unsatisfactorily compensated arterial hypertension; in the cohort of normotensive recipients, the incidence of primary hyperaldosteronism is not documented. Diagnosis of Conn's syndrome in patients in the early period after kidney transplantation is problematic, as the prevalence of arterial hypertension in transplanted patients is high (70-90%) according to the literature. Mineral abnormalities, including hypokalaemia, are also common in the early post-transplant period, mainly due to factors such as duration of cold ischaemia, onset of graft function, donor parameters, post-transplant tubulopathy, and diuretics, the effects of immunosuppressive drugs (especially calcineurin inhibitors and corticosteroids), and possibly potassium-restricted dietary habits that the patient brings from the pre-transplant period, which may mask the effect of hyperaldosteronism on potassium.We present the case of a patient who was diagnosed with Conn's syndrome 7 months after primary kidney transplantation from a deceased donor based on persistent hypokalaemia unresponsive to replacement therapy. At the time of the first manifestation of severe hypokalaemia, the patient was treated with a dual combination of antihypertensives (amlodipine at a daily dose of 5 mg and carvedilol at a daily dose of 50 mg), without the need for a diuretics.We consider the case interesting because the spectrum of mineral and acid-base abnormalities in advanced renal failure and in the early post-transplant period, as well as acid-base and mineral imbalances, including hypokalaemia, and the high prevalence of arterial hypertension in the post-transplant period, may mask the picture of Conn's syndrome (Fig. 3, Ref. 19). Text in PDF www.elis.sk Keywords: kidney transplantation, primary hyperaldosteronism, hypokalaemia, metabolic alkalosis, secondary arterial hypertension.

DOI: https://doi.org/10.4149/BLL_2024_39
Hypertension. 2024 Mar 25.

Subtype Identification of Surgically Curable Primary Aldosteronism During Treatment With Mineralocorticoid Receptor Blockade.

Giovanni Pintus, Teresa Maria Seccia, Laurence Amar, Michel Azizi, Anna Riester, Martin Reincke, Jiří Widimský, Mitsuhide Naruse, Tomaz Kocjan, Aurelio Negro, Gregory Kline, Akiyo Tanabe, Fumitoshi Satoh, Lars Christian Rump, Oliver Vonend, Peter J Fuller, Jun Yang, Nicholas Yong Nian Chee, Steven B Magill, Zulfiya Shafigullina, Marcus Quinkler, Anna Oliveras, Bo-Ching Lee, Chin-Chen Chang, Vin-Cent Wu, Zuzana Krátká, Michele Battistel, Domenico Bagordo, Brasilina Caroccia, Giulio Ceolotto, Giacomo Rossitto, Gian Paolo Rossi.

   BACKGROUND: Current guidelines and consensus documents recommend withdrawal of mineralocorticoid receptor antagonists (MRAs) before primary aldosteronism (PA) subtyping by adrenal vein sampling (AVS), but this practice can cause severe hypokalemia and uncontrolled high blood pressure. Our aim was to investigate if unilateral PA can be identified by AVS during MRA treatment.
METHODS: We compared the rate of unilateral PA identification between patients with and without MRA treatment in large data sets of patients submitted to AVS while off renin-angiotensin system blockers and β-blockers. In sensitivity analyses, the between-group differences of lateralization index values after propensity score matching and the rate of unilateral PA identification in subgroups with undetectable (≤2 mUI/L), suppressed (<8.2 mUI/L), and unsuppressed (≥8.2 mUI/L) direct renin concentration levels were also evaluated.
RESULTS: Plasma aldosterone concentration, direct renin concentration, and blood pressure values were similar in non-MRA-treated (n=779) and MRA-treated (n=61) patients with PA, but the latter required more antihypertensive agents (P=0.001) and showed a higher rate of adrenal nodules (82% versus 67%; P=0.022) and adrenalectomy (72% versus 54%; P=0.01). However, they exhibited no significant differences in commonly used AVS indices and the area under the receiving operating characteristic curve of lateralization index, both under unstimulated conditions and postcosyntropin. Several sensitivity analyses confirmed these results in propensity score matching adjusted models and in patients with undetectable, or suppressed or unsuppressed renin levels.
CONCLUSIONS: At doses that controlled blood pressure and potassium levels, MRAs did not preclude the identification of unilateral PA at AVS.
REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01234220.

Keywords:  aldosterone; blood pressure; hypertension; mineralocorticoid receptor antagonists; renin

DOI:  https://doi.org/10.1161/HYPERTENSIONAHA.124.22721
Hypertens Res. 2024 Mar 27.

Accumulating evidence suggests the potential of selective adrenal artery embolization as a standard treatment for primary aldosteronism.

Toshifumi Nakamura, Kaori Hayashi.



Keywords:  Hypertension; Primary aldosteronism; Selective adrenal artery embolization

DOI:  https://doi.org/10.1038/s41440-024-01656-0
Pflugers Arch. 2024 Mar 27.

Correction to: Histamine H2‑receptor antagonism improves conduit artery endothelial function and reduces plasma aldosterone level without lowering arterial blood pressure in angiotensin II-hypertensive mice.

Kasper B Assersen, Boye L Jensen, Camilla Enggaard, Paul M Vanhoutte, Pernille B L Hansen.

DOI: https://doi.org/10.1007/s00424-024-02955-8
Biomedicines. 2024 Mar 10. pii: 620. [Epub ahead of print]12(3):

Classical and Alternative Pathways of the Renin-Angiotensin-Aldosterone System in Regulating Blood Pressure in Hypertension and Obese Adolescents.

Adrian Martyniak, Dorota Drożdż, Przemysław J Tomasik.

  Primary hypertension (PH) is the leading form of arterial hypertension (AH) in adolescents. Hypertension is most common in obese patients, where 20 to 40% of the population has elevated blood pressure. One of the most effective mechanisms for regulating blood pressure is the renin-angiotensin-aldosterone system (RAAS). The new approach to the RAAS talks about two opposing pathways between which a state of equilibrium develops. One of them is a classical pathway, which is responsible for increasing blood pressure and is represented mainly by the angiotensin II (Ang II) peptide and, to a lesser extent, by angiotensin IV (Ang IV). The alternative pathway is responsible for the decrease in blood pressure and is mainly represented by angiotensin 1-7 (Ang 1-7) and angiotensin 1-9 (Ang 1-9). Our research study aimed to assess changes in angiotensin II, angiotensin IV, angiotensin 1-7, and angiotensin 1-9 concentrations in the plasma of adolescents with hypertension, with hypertension and obesity, and obesity patients. The Ang IV concentration was lower in hypertension + obesity versus control and obesity versus control, respectively p = 0.01 and p = 0.028. The Ang 1-9 concentration was lower in the obesity group compared to the control group (p = 0.036). There were no differences in Ang II and Ang 1-7 peptide concentrations in the hypertension, hypertension and obesity, obesity, and control groups. However, differences were observed in the secondary peptides, Ang IV and Ang 1-9. In both cases, the differences were related to obesity.

Keywords:  angiotensin 1–7; angiotensin 1–9; angiotensin II; angiotensin IV; arterial hypertension; obesity

DOI:  https://doi.org/10.3390/biomedicines12030620
Cells. 2024 Mar 08. pii: 476. [Epub ahead of print]13(6):

Phosphodiesterases 4B and 4D Differentially Regulate cAMP Signaling in Calcium Handling Microdomains of Mouse Hearts.

Axel E Kraft, Nadja I Bork, Hariharan Subramanian, Nikoleta Pavlaki, Antonio V Failla, Bernd Zobiak, Marco Conti, Viacheslav O Nikolaev.

  The ubiquitous second messenger 3',5'-cyclic adenosine monophosphate (cAMP) regulates cardiac excitation-contraction coupling (ECC) by signaling in discrete subcellular microdomains. Phosphodiesterase subfamilies 4B and 4D are critically involved in the regulation of cAMP signaling in mammalian cardiomyocytes. Alterations of PDE4 activity in human hearts has been shown to result in arrhythmias and heart failure. Here, we sought to systematically investigate specific roles of PDE4B and PDE4D in the regulation of cAMP dynamics in three distinct subcellular microdomains, one of them located at the caveolin-rich plasma membrane which harbors the L-type calcium channels (LTCCs), as well as at two sarco/endoplasmic reticulum (SR) microdomains centered around SR Ca2+-ATPase (SERCA2a) and cardiac ryanodine receptor type 2 (RyR2). Transgenic mice expressing Förster Resonance Energy Transfer (FRET)-based cAMP-specific biosensors targeted to caveolin-rich plasma membrane, SERCA2a and RyR2 microdomains were crossed to PDE4B-KO and PDE4D-KO mice. Direct analysis of the specific effects of both PDE4 subfamilies on local cAMP dynamics was performed using FRET imaging. Our data demonstrate that all three microdomains are differentially regulated by these PDE4 subfamilies. Whereas both are involved in cAMP regulation at the caveolin-rich plasma membrane, there are clearly two distinct cAMP microdomains at the SR formed around RyR2 and SERCA2a, which are preferentially controlled by PDE4B and PDE4D, respectively. This correlates with local cAMP-dependent protein kinase (PKA) substrate phosphorylation and arrhythmia susceptibility. Immunoprecipitation assays confirmed that PDE4B is associated with RyR2 along with PDE4D. Stimulated Emission Depletion (STED) microscopy of immunostained cardiomyocytes suggested possible co-localization of PDE4B with both sarcolemmal and RyR2 microdomains. In conclusion, our functional approach could show that both PDE4B and PDE4D can differentially regulate cardiac cAMP microdomains associated with calcium homeostasis. PDE4B controls cAMP dynamics in both caveolin-rich plasma membrane and RyR2 vicinity. Interestingly, PDE4B is the major regulator of the RyR2 microdomain, as opposed to SERCA2a vicinity, which is predominantly under PDE4D control, suggesting a more complex regulatory pattern than previously thought, with multiple PDEs acting at the same location.

Keywords:  FRET; cAMP; calcium cycling; microdomain; phosphodiesterase

DOI:  https://doi.org/10.3390/cells13060476
Commun Biol. 2024 Mar 27. 7(1): 369

TRPM5 activation depends on a synergistic effect of calcium and PKC phosphorylation.

Alaa Nmarneh, Avi Priel.

Transient receptor potential melastatin 5 (TRPM5) is a calcium-activated monovalent-specific ion channel involved in insulin secretion and taste transduction, making it an attractive target for drug development in various pathologies. While TRPM5 activation involves ligand binding to Gq/G-protein coupled receptors (GPCR) and subsequent elevation of intracellular calcium levels, recent reports suggest the need for additional molecular determinants. Hence, the mechanism of TRPM5 activation remains to be elucidated. Here, we show that PKC phosphorylation and the elevation of intracellular Ca2+ levels are required for TRPM5 activation, with PKC phosphorylation being crucial for channel-evoked currents, primarily at physiological membrane potentials. In contrast, physiological relevant calcium levels alone only induce TRPM5 activation at positive voltages. Our findings highlight the necessity of coordinated intracellular calcium release and PKC phosphorylation for TRPM5 activation. Thus, our results suggest that regulation of PKC activity could be a promising therapeutic target for diseases associated with TRPM5 modulation.

DOI: https://doi.org/10.1038/s42003-024-06054-3
Hypertens Res. 2024 Mar 28.

Prediction of endogenous mineralocorticoid receptor activity by depressor effects of mineralocorticoid receptor antagonists in patients with primary aldosteronism.

Makiko Ikemoto, Satoshi Morimoto, Atsuhiro Ichihara.

  Patients with primary aldosteronism have an increased risk of developing cardiovascular disease. The response to mineralocorticoid receptor antagonists varies among individuals, indicating diverse mineralocorticoid receptor activities in these patients. This study explored the factors linked to the efficacy of blood pressure reduction through mineralocorticoid receptor antagonists in patients with primary aldosteronism. We examined the relationship between the reduction in blood pressure and patient characteristics in a group of 41 patients with primary aldosteronism (24 males, mean age 55 ± 13 years, including 34 patients diagnosed with bilateral primary aldosteronism) before and after undergoing treatment with mineralocorticoid receptor antagonists. Significant reductions in office blood pressure were observed 3 and 6 months after treatment initiation. Single correlation analyses showed that the urinary chloride-to-potassium ratio displayed the strongest positive association with blood pressure reduction, surpassing plasma aldosterone concentration, plasma renin activity, and urinary sodium-to-potassium ratio, at 3 and 6 months. Multiple correlation analyses revealed a consistent and independent positive correlation between the urinary chloride-to-potassium ratio and blood pressure reduction at 3 and 6 months. The optimal threshold for the urinary chloride-to-potassium ratio with respect to its ability to lower blood pressure, was determined as 3.18. These results imply that the urinary chloride-to-potassium ratio may be independently associated with the effectiveness of blood pressure reduction facilitated by mineralocorticoid receptor antagonists. Moreover, it could potentially serve as a valuable predictor of the effectiveness of these agents and function as an indicator of endogenous mineralocorticoid receptor activity in patients with primary aldosteronism.

Keywords:  Chloride; Hypertension; Potassium; Rac1; Sodium

DOI:  https://doi.org/10.1038/s41440-024-01651-5
J Hypertens. 2024 Mar 11.

Effect of adrenocorticotropic hormone stimulation during adrenal vein sampling for the subtyping of primary aldosteronism: a prospective study.

Fan Yang, Yijie Wang, Ziwei Zhang, Yangjie Zeng, Mengsi Liu, Zhaoyang Tian, Ping Li.

OBJECTIVE: Adrenal venous sampling (AVS) is key for primary aldosteronism subtype identification. However, the value of adrenocorticotropic hormone (ACTH) stimulation in AVS is still controversial.
METHODS: In this prospective study, we investigated the role of continuous ACTH infusion on the performance and interpretation of bilateral simultaneous AVS using a standard protocol in 59 primary aldosteronism patients. We analyzed the selectivity index and lateralization index in AVS pre and post-ACTH and estimated the prognosis of patients who underwent adrenalectomy with different cutoff points of lateralization index post-ACTH.
RESULTS: The confirmed success rate of bilateral adrenal vein catheterization increased from 84% pre-ACTH to 95% post-ACTH. Fifty percent of the patients had a decline in lateralization index post-ACTH, 30% of patients showed unilateral primary aldosteronism pre-ACTH but bilateral primary aldosteronism post-ACTH according to lateralization index at least 2 pre-ACTH and lateralization index at least 4 post-ACTH. The outcomes of the patients with primary aldosteronism after adrenalectomy indicated that all patients achieved clinical and biochemical success regardless of lateralization index at least 4 or less than 4 post-ACTH. Receiver operating characteristic curves showed that lateralization index cutoff 2.58 post-ACTH stimulation yielded the best threshold in lateralization with a sensitivity of 73.1% and a specificity of 92.9%.
CONCLUSION: ACTH stimulation increased the AVS success rates in patients with primary aldosteronism, reduced lateralization index in some cases and decreased the proportion of identified unilateral primary aldosteronism, resulting in some patients losing the opportunity for disease cure. Compared with lateralization index at least 4, a lower cutoff point of lateralization index at least 2.58 after ACTH stimulation has better accuracy of lateralization diagnosis.

DOI: https://doi.org/10.1097/HJH.0000000000003684
J Endocrinol Invest. 2024 Mar 27.

Development of a diagnostic model for pre-washout screening of primary aldosteronism.

Q Wang, H Dong, H-W Li, Z-H Zheng, Y-Z Liu, Y-H Hua, Y-J Xiong, H-M Zhang, L Song, Y-B Zou, X-J Jiang.

   PURPOSE: Primary aldosteronism (PA) diagnosis is affected by antihypertensive drugs that are commonly taken by patients with suspected PA. In this study, we developed and validated a diagnostic model for screening PA without drug washout.
METHODS: We retrospectively analyzed 1095 patients diagnosed with PA or essential hypertension. Patients were randomly grouped into training and validation sets at a 7:3 ratio. Baseline characteristics, plasma aldosterone concentration (PAC), and direct renin concentration (DRC) before and after drug washout were separately recorded, and the aldosterone-to-renin ratio (ARR) was calculated.
RESULTS: PAC and ARR were higher and direct renin concentration was lower in patients with PA than in patients with essential hypertension. Furthermore, the differences in blood potassium and sodium concentrations and hypertension grades between the two groups were significant. Using the abbreviations potassium (P), ARR (A), PAC (P), sodium (S), and hypertension grade 3 (3), the model was named PAPS3. The PAPS3 model had a maximum score of 10, with the cutoff value assigned as 5.5; it showed high sensitivity and specificity for screening PA in patients who exhibit difficulty in tolerating drug washout.
CONCLUSION: PA screening remains crucial, and standard guidelines should be followed for patients to tolerate washout. The PAPS3 model offers an alternative to minimize risks and enhance diagnostic efficiency in PA for those facing washout challenges. Despite its high accuracy, further validation of this model is warranted through large-scale clinical studies.

Keywords:  Aldosterone; Aldosterone-to-renin ratio; Primary aldosteronism; Renin; Screening

DOI:  https://doi.org/10.1007/s40618-024-02337-y
Pharmaceuticals (Basel). 2024 Feb 24. pii: 293. [Epub ahead of print]17(3):

TRPV4 Activation during Guinea Pig Airway Smooth Muscle Contraction Promotes Ca2+ and Na+ Influx.

Luis M Montaño, Abril Carbajal-García, María F Casas-Hernández, David Arredondo-Zamarripa, Jorge Reyes-García.

  Airway smooth muscle (ASM) contraction is determined by the increase in intracellular Ca2+ concentration ([Ca2+]i) caused by its release from the sarcoplasmic reticulum (SR) or by extracellular Ca2+ influx. Major channels involved in Ca2+ influx in ASM cells are L-type voltage-dependent Ca2+ channels (L-VDCCs) and nonselective cation channels (NSCCs). Transient receptor potential vanilloid 4 (TRPV4) is an NSCC recently studied in ASM. Mechanical stimuli, such as contraction, can activate TRPV4. We investigated the possible activation of TRPV4 by histamine (His)- or carbachol (CCh)-induced contraction in guinea pig ASM. In single myocytes, the TRPV4 agonist (GSK101) evoked an increase in [Ca2+]i, characterized by a slow onset and a plateau phase. The TRPV4 antagonist (GSK219) decreased channel activity by 94%, whereas the Ca2+-free medium abolished the Ca2+ response induced by GSK101. Moreover, GSK101 caused Na+ influx in tracheal myocytes. GSK219 reduced the Ca2+ peak and the Ca2+ plateau triggered by His or CCh. TRPV4 blockade shifted the concentration-response curve relating to His and CCh to the right in tracheal rings and reduced the maximal contraction. Finally, the activation of TRPV4 in single myocytes increased the Ca2+ refilling of the SR. We conclude that contraction of ASM cells after stimulation with His or CCh promotes TRPV4 activation, the subsequent influx of Ca2+ and Na+, and the opening of L-VDCCs. The entry of Ca2+ into ASM cells via TRPV4 and L-VDCCs contributes to optimal smooth muscle contraction.

Keywords:  TRPV4; airway smooth muscle; asthma; intracellular Ca2+ concentration; smooth muscle contraction

DOI:  https://doi.org/10.3390/ph17030293
J Appl Lab Med. 2024 Mar 27. pii: jfae017. [Epub ahead of print]

Screening for Primary Aldosteronism by Mass Spectrometry Versus Immunoassay Measurements of Aldosterone: A Prospective Within-Patient Study.

Sybille Fuld, Georgiana Constantinescu, Christina Pamporaki, Mirko Peitzsch, Manuel Schulze, Jun Yang, Lisa Müller, Aleksander Prejbisz, Andrzej Januszewicz, Hanna Remde, Lydia Kürzinger, Ulrich Dischinger, Matthias Ernst, Sven Gruber, Martin Reincke, Felix Beuschlein, Jacques W M Lenders, Graeme Eisenhofer.

BACKGROUND: Measurements of aldosterone by mass spectrometry are more accurate and less prone to interferences than immunoassay measurements, and may produce a more accurate aldosterone:renin ratio (ARR) when screening for primary aldosteronism (PA).
METHODS: Differences in diagnostic performance of the ARR using mass spectrometry vs immunoassay measurements of aldosterone were examined in 710 patients screened for PA. PA was confirmed in 153 patients and excluded in 451 others. Disease classifications were not achieved in 106 patients. Areas under receiver-operating characteristic curves (AUROC) and other measures were used to compare diagnostic performance.
RESULTS: Mass spectrometry-based measurements yielded lower plasma aldosterone concentrations than immunoassay measurements. For the ARR based on immunoassay measurements of aldosterone, AUROCs were slightly lower (P = 0.018) than those using mass spectrometry measurements (0.895 vs 0.906). The cutoff for the ARR to reach a sensitivity of 95% was 30 and 21.5 pmol/mU by respective immunoassay and mass spectrometry-based measurements, which corresponded to specificities of 57% for both. With data restricted to patients with unilateral PA, diagnostic sensitivities of 94% with specificities >81% could be achieved at cutoffs of 61 and 52 pmol/mU for respective immunoassay and mass spectrometry measurements.
CONCLUSIONS: Mass spectrometry-based measurements of aldosterone for the ARR provide no clear diagnostic advantage over immunoassay-based measurements. Both approaches offer limited diagnostic accuracy for the ARR as a screening test. One solution is to employ the higher cutoffs to triage patients likely to have unilateral PA for further tests and possible adrenalectomy, while using the lower cutoffs to identify others for targeted medical therapy.German Clinical Trials Register ID: DRKS00017084.

DOI: https://doi.org/10.1093/jalm/jfae017
Hypertension. 2024 Mar 28.

Salt-Sensitive Hypertension and the Kidney.

Mitsuhiro Nishimoto, Karen Griffin, Brandi M Wynne, Toshiro Fujita.

  Salt-sensitive hypertension (SS-HT) is characterized by blood pressure elevation in response to high dietary salt intake and is considered to increase the risk of cardiovascular and renal morbidity. Although the mechanisms responsible for SS-HT are complex, the kidneys are known to play a central role in the development of SS-HT and the salt sensitivity of blood pressure (SSBP). Moreover, several factors influence renal function and SSBP, including the renin-angiotensin-aldosterone system, sympathetic nervous system, obesity, and aging. A phenotypic characteristic of SSBP is aberrant activation of the renin-angiotensin system and sympathetic nervous system in response to excessive salt intake. SSBP is also accompanied by a blunted increase in renal blood flow after salt loading, resulting in sodium retention and SS-HT. Obesity is associated with inappropriate activation of the aldosterone mineralocorticoid receptor pathway and renal sympathetic nervous system in response to excessive salt, and mineralocorticoid receptor antagonists and renal denervation attenuate sodium retention and inhibit salt-induced blood pressure elevation in obese dogs and humans. SSBP increases with age, which has been attributed to impaired renal sodium handling and a decline in renal function, even in the absence of kidney disease. Aging-associated changes in renal hemodynamics are accompanied by significant alterations in renal hormone levels and renal sodium handling, resulting in SS-HT. In this review, we focus mainly on the contribution of renal function to the development of SS-HT.

Keywords:  aging; aldosterone; hypertension; kidney; sodium

DOI:  https://doi.org/10.1161/HYPERTENSIONAHA.123.21369